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B-H curve of nonlinear material and constitutive relation

Posted Aug 26, 2013, 11:23 p.m. EDT Low-Frequency Electromagnetics Version 4.3a 1 Reply

Xin Wei
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question1: In the calculation of magnetic field , I have a expression of B-H curve, is B=B(H). Then in the "Ampere's Law", When constitutive relation is "B=mu0*(H+M)", what shoud be filled in the magnetization intensity M? If it is M(H), I can get it from "M=B(H)/mu0-H". How do I write the M(H)? If not, what should I write?

question2: In transient calculation, I have three B-H curves, are B1(H), B2(H) B3(H), and have three i-t curves, are i1(t), i2(t) i3(t), and they are corresponded. When exciting current is i1(t), the B-H curve used is B1(H); When exciting current is i2(t), the B-H curve used is B2(H);When exciting current is i3(t), the B-H curve used is B3(H). it makes different current is corresponded with different B-H curve. In comsol 4.3b, how I achieve it？

thank you


1 Reply Last Post Sep 16, 2013, 5:45 a.m. EDT
Lingling Tang
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Posted: 1 decade ago Sep 16, 2013, 5:45 a.m. EDT

question1: In the calculation of magnetic field , I have a expression of B-H curve, is B=B(H). Then in the "Ampere's Law", When constitutive relation is "B=mu0*(H+M)", what shoud be filled in the magnetization intensity M? If it is M(H), I can get it from "M=B(H)/mu0-H". How do I write the M(H)? If not, what should I write?

question2: In transient calculation, I have three B-H curves, are B1(H), B2(H) B3(H), and have three i-t curves, are i1(t), i2(t) i3(t), and they are corresponded. When exciting current is i1(t), the B-H curve used is B1(H); When exciting current is i2(t), the B-H curve used is B2(H);When exciting current is i3(t), the B-H curve used is B3(H). it makes different current is corresponded with different B-H curve. In comsol 4.3b, how I achieve it？

thank you


first, if you define the magnetic material's constitutive relation as B=B(H) or H=H(B), mostly this is a soft magnetic material, and in Ampere's law you need to choose the user-defined relation as H=H(B) or B=B(H);
if you choose "B=mu0*(H+M)", the M shall be calculated from you B=B(H) relation, and read more about electromagnetics!
second question, do it three times!
[QUOTE] question1: In the calculation of magnetic field , I have a expression of B-H curve, is B=B(H). Then in the "Ampere's Law", When constitutive relation is "B=mu0*(H+M)", what shoud be filled in the magnetization intensity M? If it is M(H), I can get it from "M=B(H)/mu0-H". How do I write the M(H)? If not, what should I write? question2: In transient calculation, I have three B-H curves, are B1(H), B2(H) B3(H), and have three i-t curves, are i1(t), i2(t) i3(t), and they are corresponded. When exciting current is i1(t), the B-H curve used is B1(H); When exciting current is i2(t), the B-H curve used is B2(H);When exciting current is i3(t), the B-H curve used is B3(H). it makes different current is corresponded with different B-H curve. In comsol 4.3b, how I achieve it？ thank you [/QUOTE] first, if you define the magnetic material's constitutive relation as B=B(H) or H=H(B), mostly this is a soft magnetic material, and in Ampere's law you need to choose the user-defined relation as H=H(B) or B=B(H); if you choose "B=mu0*(H+M)", the M shall be calculated from you B=B(H) relation, and read more about electromagnetics! second question, do it three times!

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